Bathymetric and seasonal changes in photosynthesis and respiration of the phototrophic sponge Phyllospongia lamellosa in comparison with respiration by the heterotrophic sponge Ianthella basta on Davies Reef, Great Barrier Reef

Abstract

The phototrophic sponge Phyllospongia lamellosa is found to depths of 30 m on Davies Reef. Studies of the photophysiology show that this corresponds to the depth at which the sponge–symbiont system can meet 80% of its daily respiratory carbon needs photosynthetically. Net 24-h production was constant to a depth of 20 m (20 µmol O2 g-1 fresh weight day -1 ) and then decreased to compensatory levels at 25 m. The maintenance of net 24-h production to a depth of 20 m was characterized by reductions in the sub-saturating light intensity (Ik ), indicating increased efficiency of light usage at depth. At depths greater than 20 m the changes in Ik could not compensate for the reduced light intensity. The respiration rate of Phyllospongia (3–5 µmol O2 g-1 fresh weight h-1 ) was significantly greater than that of the heterotrophic sponge Ianthella (2.0–3.6 µmol O2 g-1 fresh weight h-1 ) to an extent that depended on season and location. Respiration rates for both species changed similarly between seasons, being higher in summer. There was no evidence for increased respiration rates in shallower water (<10 m), suggesting that this is not a cause for the reduced occurrence of Phyllospongia in shallow waters.

Incongruence between the distribution of a common coral reef sponge and photosynthesis

“…Two suspended 400 W metal halide lamps (Eye) were used to adjust the light intensity over the respirometry chambers, exposing the sponges to 12 discrete light levels for 25 min periods (0,15,40,60,100,120,200,290,420,530,710 and 900 µmol photons m -2 s -1 ). Measuring across this range of light levels allows a good characterisation of the shape of the photosynthesisirradiance response (Hoogenboom et al 2006), and is representative of light levels experienced on the GBR at the depths where R. odorabile are commonly found (Fabricius & Klumpp 1995, Cheshire et al 1997. Dis-crete light levels were measured using a LI-192S LI-COR probe connected to a LI-1000 data logger.…”

“…2). Furthermore, molecular analysis of > 85 000 sequences of R. odorabile symbionts showed that cyanobacteria comprise < 0.71% of the sequenced microbial community (Webster et al 2010).97 Mar Ecol Prog Ser 423: 95-100,Several studies have linked the photosynthetic activity of marine sponges to the presence of cyanobacteria within the tissues (Wilkinson 1983, Cheshire et al 1997, Erwin & Thacker 2008. Nevertheless, even if present in Rhopaloeides odorabile, photosymbionts do not provide this species with carbon generated through photosynthesis.…”

“…Bio-filtration, foam fractionators and sand filters were used to maintain water quality. Each aquarium was illuminated on a 10 h light:14 h dark regime using 400 W metal halide lamps (Eye) at approximately 500 µmol photons m -2 s -1, representative of near-natural light regimes (Fabricius & Klumpp 1995, Cheshire et al 1997.Photophysiology. To quantify photosynthesis within the tissues of Rhopaloeides odorabile, oxygen evolution was measured using a set of 6 closed, recirculating perspex respirometry (flow) chambers (2.7 l) fitted with calibrated Clark-type oxygen electrodes (Cheshire Systems).…”

Sponge-Associated Microorganisms: Evolution, Ecology, and Biotechnological Potential

“…Heterotrophy is a common form of carbon metabolism in sponges, either via consumption of microbes from seawater or via microbial uptake of dissolved organic carbon (495). However, for many sponges, particularly those in tropical regions, carbon metabolism centers around the activities of photosynthetic microorganisms, such as cyanobacteria (11,58,59,381,470,474,477,486). Many tropical sponges contain substantial populations of these oxygenic autotrophs, and nowhere is the contribution of microbial symbionts to the host sponge more evident than in this case (see also the next section).…”

Experimental manipulation of shade, silt, nutrients and salinity on the temperate reef sponge Cymbastela concentrica

“…from reefs in southern temperate Australia were probably phototrophic, whilst Roberts et al (1999) provided evidence that a surprisingly high proportion of temperate reef sponge species (including Cymbastela concentrica) also had this potential. Thus, it would appear that C. concentrica relies on its symbionts for at least some of its nutritional requirements, and this is likely to be compromised under conditions that limit the amount of light available for photosynthesis (Cheshire et al 1997). …”